ND will do what they've done vs elite talent teams the past 35 years.
Lose.
Just watch the 2012 NCG vs Alabama.
Or the playoff game vs Clemson in 2018.
Or the playoff game vs Alabama in 2020.
This year? They haven't played an elite team. You could stretch and say UGA, but with their backup QB. Penn State? ND's mirror, totally imasculated by big-boy teams going back decades. Literally, since 1994, their only big wins late in the year were followed by losses to USC in the RB. It's a joke.
ND's only chance is that it's very difficult to "get up" for 4 straight games (themselves included) and random chance happens to avalanche their way. An ND win would be a statistical outlier, plain and simple.